Tetrahymena thermophila
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ABSTRACT:
PROVIDER: PRJNA168025 | ENA |
REPOSITORIES: ENA
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Project description:Emerging evidence suggests that Ago/Piwi proteins function in the nucleus as well as the cytoplasm to control gene expression, but the mechanisms they employ in the nucleus remain poorly defined. The Tetrahymena thermophila Ago/Piwi protein Twi12 is essential for growth and functions in the nucleus. We show that Twi12 interacts with the exonuclease Xrn2. Twi12 functions to stabilize and localize Xrn2 in vivo, as well as activate its exonuclease activity in vitro. When Twi12 or Xrn2 are depleted, pre-rRNA processing intermediates accumulate and mature rRNA levels decline. RNA polymerase I and II (RNAP I and II) transcripts also accumulate. Twi12 function depends on small RNA (sRNA) binding, which is required for its nuclear import. Twi12-bound sRNAs are Dicer-independent 3' tRNA fragments that we propose may not be involved in sequence-specific base pairing to targets. Our findings suggest a role for tRNA fragments and an Ago/Piwi protein in global control of gene expression through interaction with a conserved exonuclease.
2012-08-31 | GSE38507 | GEO
Project description:Emerging evidence suggests that Ago/Piwi proteins function in the nucleus as well as the cytoplasm to control gene expression, but the mechanisms they employ in the nucleus remain poorly defined. The Tetrahymena thermophila Ago/Piwi protein Twi12 is essential for growth and functions in the nucleus. We show that Twi12 interacts with the exonuclease Xrn2. Twi12 functions to stabilize and localize Xrn2 in vivo, as well as activate its exonuclease activity in vitro. When Twi12 or Xrn2 are depleted, pre-rRNA processing intermediates accumulate and mature rRNA levels decline. RNA polymerase I and II (RNAP I and II) transcripts also accumulate. Twi12 function depends on small RNA (sRNA) binding, which is required for its nuclear import. Twi12-bound sRNAs are Dicer-independent 3' tRNA fragments that we propose may not be involved in sequence-specific base pairing to targets. Our findings suggest a role for tRNA fragments and an Ago/Piwi protein in global control of gene expression through interaction with a conserved exonuclease. One library is analyzed here: small RNAs associated with ZZF-tagged Twi12. Twi12 is the full-length version, which is extended by 17 amino acids at the N-terminus compared to the previously-reported Twi12. Specifically, the 16-22 nt reads were analyzed here.
2012-08-31 | E-GEOD-38507 | biostudies-arrayexpress
Project description:Argonaute/Piwi proteins associate with small RNAs that typically provide sequence specificity for RNP function in gene and genome regulation. Here we show that Twi12, a Tetrahymena Piwi protein essential for growth, is loaded with mature tRNA fragments. The tightly bound ~18-22 nt tRNA 3’ fragments are biochemically distinct from the tRNA halves produced transiently in response to stress. Notably, the end positions of Twi12-bound tRNA 3' fragments precisely match RNAs detected in total small RNA of mouse embryonic stem cells and human cancer cells. Our studies demonstrate unanticipated evolutionary conservation of mature tRNA processing to tRNA-fragment small RNAs.
2010-10-26 | GSE24916 | GEO
Project description:Argonaute/Piwi proteins associate with small RNAs that typically provide sequence specificity for RNP function in gene and genome regulation. Here we show that Twi12, a Tetrahymena Piwi protein essential for growth, is loaded with mature tRNA fragments. The tightly bound ~18-22 nt tRNA 3M-bM-^@M-^Y fragments are biochemically distinct from the tRNA halves produced transiently in response to stress. Notably, the end positions of Twi12-bound tRNA 3' fragments precisely match RNAs detected in total small RNA of mouse embryonic stem cells and human cancer cells. Our studies demonstrate unanticipated evolutionary conservation of mature tRNA processing to tRNA-fragment small RNAs. Two libraries are analyzed here: sRNAs associated with slightly overexpressed ZZ-tagged Twi12 purified under native conditions (size range 15-34nt), and those associated after formaldehyde crosslinking (15-22nt).
2010-10-26 | E-GEOD-24916 | biostudies-arrayexpress
Project description:A growth-essential Tetrahymena Piwi protein carries tRNA fragment cargo
| PRJNA132107 | ENA
Project description:Sequence, Biogenesis, and Function of Diverse sRNA Classes Bound to the Piwi-family Proteins of Tetrahymena thermophila
| PRJNA117745 | ENA
Project description:PAZ/PIWI-domain (PPD) proteins carrying small RNAs (sRNAs) function in gene and genome regulation. The ciliate Tetrahymena thermophila encodes numerous PPD proteins exclusively of the Piwi clade. We show that the three Tetrahymena Piwi-family proteins (Twis) preferentially expressed in growing cells differ in their genetic essentiality and subcellular localization. Affinity purification of all eight distinct Twi proteins revealed unique properties of their bound sRNAs. Deep sequencing of Twi-bound and total sRNAs in strains disrupted for various silencing machinery uncovered an unanticipated diversity of 23-24 nt sRNA classes in growing cells, each with distinct genetic requirements for accumulation. Altogether Twis distinguish sRNAs derived from loci of pseudogene families, three types of DNA repeats, structured RNAs, and EST-supported loci with convergent or paralogous transcripts. Most surprisingly, Twi7 binds complementary strands of unequal length while Twi10 binds a specific permutation of the guanosine-rich telomeric repeat. These studies greatly expand the structural and functional repertoire of endogenous sRNAs and RNPs. 11 libraries were analyzed. 5 are total sRNA (from knockout strains or WT background strains), and 6 are Argonaute-bound sRNA
2009-11-23 | E-GEOD-17006 | biostudies-arrayexpress
Project description:PAZ/PIWI-domain (PPD) proteins carrying small RNAs (sRNAs) function in gene and genome regulation. The ciliate Tetrahymena thermophila encodes numerous PPD proteins exclusively of the Piwi clade. We show that the three Tetrahymena Piwi-family proteins (Twis) preferentially expressed in growing cells differ in their genetic essentiality and subcellular localization. Affinity purification of all eight distinct Twi proteins revealed unique properties of their bound sRNAs. Deep sequencing of Twi-bound and total sRNAs in strains disrupted for various silencing machinery uncovered an unanticipated diversity of 23-24 nt sRNA classes in growing cells, each with distinct genetic requirements for accumulation. Altogether Twis distinguish sRNAs derived from loci of pseudogene families, three types of DNA repeats, structured RNAs, and EST-supported loci with convergent or paralogous transcripts. Most surprisingly, Twi7 binds complementary strands of unequal length while Twi10 binds a specific permutation of the guanosine-rich telomeric repeat. These studies greatly expand the structural and functional repertoire of endogenous sRNAs and RNPs.
2009-11-23 | GSE17006 | GEO
Project description:Tetrahymena thermophila Raw sequence reads
| PRJNA611686 | ENA